Functional-Gradient-Structured Ultra-High Modulus Solid Polymer Electrolyte for All-Solid-State Lithium Metal Batteries
It was a contradiction between achieving high modulus of solid polymer electrolyte (SPE) and good interface contact in all-solid-state lithium metal batteries, which can contribute prohibiting the dendrite growth and the increase of cell cyclability, respectively. Herein we report a new functional-gradient-structured ultra-high modulus SPE (6.67 GPa) by integrating ceramic-rich phase and polymer-rich phase. The ceramic-rich phase physically prohibits the dendrite growth and the polymer-rich phase improves the interface compatibility between the cathode and electrolyte. As a result, this ultra-high modulus solid polymer electrolyte renders the FG-SPE based symmetrical batteries to a low charging voltage polarization at 0.5 mAh cm−2. The resulted all-solid-state Li/LiFePO4 batteries show a high specific capacity of 163.2 mAh g−1 at 0.1 C, and a high reversible capacity still be obtained even at 2 C rate. Importantly, the active material can achieve a high mass loading of 15.6 mg cm−2, which is significant for practical application.